Isovector correlations and pion single charge exchange reactions in light nuclei |
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Authors: | J Warszawski A Gal JM Eisenberg |
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Institution: | Department of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Israel;Racah Institute of Physics, Hebrew University of Jerusalem, Israel;Department of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Israel |
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Abstract: | The reactions 7Li(π+, π0)7Be(g.s.), 7Li(π+, π0)7Be1(429keV) and 13C(π+, π0)13N(g.s.) are treated in DWIA, including corrections arising from two-step processes in which an intermediate state is reached in the course of the charge exchange. The distortions are introduced by means of a first-order optical potential; no special assumptions of extreme high energy limits are made. The closure sum over intermediate states in the two-step charge exchange mechanism leads to an isovector two-particle correlation function whose properties for p-shell nuclei are discussed in detail. Consequences of the introduction of effective transition operators for the single-step mechanism, with and without spin-flip, and for the two-step contribution are discussed, as are the allowable modifications in nuclear shell radii consistent with present knowledge of Coulomb energies. Comparison is made with experiment — in the case of the separated 7Be states, for the first time — and with other theoretical approaches. |
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